What does it mean if antibody test results say 1:25,000?

I just remember my results saying this years ago when having thyroid antibodies tested. I didn't know enough at that stage to ask?

[Spareribs]

Sorry you haven't had a response yet - I'll bump it up via newsfeed J

(I've no idea)

[helvella Administrator Thyroid UK]

I think it an expression of how dilute the sample can be and still be detected. However, I really have no idea how to "convert" it into the currently more usual ways of expressing it and, anyway, I think it is likely to be fairly dependent on the actual analysis kit used.

Rod